Coumarins are a group of widely used laser dyes that emit blue-green light. 7-diethylamino-4-methylcoumarin was the first coumarin laser dye that exhibits laser action at around 460nm during flash lamp excitation. Its amino analog, 7-amino-4-methylcoumarin or coumarin 120, exhibits laser action at 440nm. The basic chromophore in certain dyes is replaced with its heterocyclic analogs, such as aza-quinolone, quinolone, or aza-coumarin, to improve its dye characteristics.
Coumarin dye lasers have low photostability and degrade due to laser light. The laser may produce undesired effects when the byproducts formed during degradation absorb light in the laser region. Coumarin molecule is non-fluorescent and displays intense fluorescence properties upon the substitution of functional groups at different positions.
The beam intensity of the coumarin laser dye is restricted by saturation and cannot be enhanced over a specific pump power range, due to its photo-quenching effect.
Some of the commercial coumarin laser dyes include coumarin 102, coumarin 466, coumarin 2, coumarin 4, coumarin 152A, coumarin 152, coumarin 522, coumarin 500, etc.
||Flash lamp or other lasers
A coumarin dye laser is capable of producing subnanosecond, millijoule pulses that are applied in fast photochemical reaction studies, or for pumping other dye lasers. Manufacturing dye-intercalated nanocomposite clays in non-linear and linear optical fields is another potential application of coumarin dye laser.
Other common applications of coumarin dye laser include:
- Optical brightening agents
- Food preservatives
Sources and Further Reading